The present invention relates to an X-ray transmission inspection apparatus which is capable of detecting minute foreign matters and the like in a sample and which can easily perform adjustment such as calibration of inspection.
Generally, in order to detect foreign matters such as minute metals or the like in a sample, an X-ray transmission inspection is used in which an X-ray transmission image acquired by irradiating X-rays to the sample is inspected. For example, in recent years, in lithium-ion secondary batteries adopted in automobiles, hybrid vehicles, electric vehicles, and the like, an electrode, as an anode, is formed in such a manner that a lithium manganese oxide film or a lithium cobalt oxide film is formed on both surfaces of an Al film. Therefore, if foreign matters, such as Fe (iron), SUS (stainless) or the like, of several tens of micrometers or lager are mixed into the battery, a short circuit may occur, thereby causing burning of the battery or degradation of performance. Therefore, mixed foreign matters are detected by X-ray transmission inspection and removed during production.
In an X-ray transmission inspection apparatus for detecting foreign matters or the like in a sample, it is well known that, when conducting an in-line inspection, an X-ray source and an X-ray detector such as a line sensor are arranged to face each other with a sample moving in one direction placed therebetween. For example, a convention solution proposes an X-ray foreign matter inspection apparatus that detects even a minute foreign matter with high sensitivity by using a time delay integration sensor (TDI sensor). In this X-ray foreign matter inspection apparatus, foreign matters are detected by synchronizing the moving speed of the sample with the charge transfer speed of the TDI sensor.
The above-described conventional technique poses the following problems. That is, in the conventional X-ray transmission inspection apparatus, when it is desired to perform adjustment (calibration or the like) of the X-ray source and the X-ray detector by using a standard sample whose size and position are previously known, since the X-ray source and the X-ray detector have been arranged so as to face a moving sample, it was necessary to inspect the standard sample by placing the standard sample placed at the same position as the sample instead of the sample. In addition, after the inspection of the standard sample, it was also necessary to reposition the sample to its original position. For this reason, an operation of replacing the sample with the standard sample is necessary, which causes a problem that the inspection operation must be interrupted for a long time. Particularly, when a belt-shaped sample is inspected, since the inspection is performed while the sample flows continuously by a roll-to-roll method, it is difficult to perform the inspection by interrupting the inspection and replacing the sample with the standard sample.